While most companies are acutely aware of the hazards of ESD (electrostatic discharge), few are aware of best practices for preventing failures of today’s extremely sensitive devices often referred to as Class 0. Class 0 Definition We have found, however, that manufacturing failure rates escalate sharply for devices with ESD withstand voltages below 250 volts for either HBM or CDM. MM is intentionally omitted from this discussion since it is largely redundant to HBM. Virtually all factories will have these devices within the next year and most are ill prepared. However, factories that have incorporated our Best Practices have virtually eliminated ESD failures even for Class 000.
The counter measures for Class 0 invariably require complex customized solutions that are not addressed by any industry or military standard nor do these standards define the term Class 0 for manufacturing. The rapid advancements in device technology and the complex customization make it difficult for standards organizations to keep pace. As a result, it is unlikely that any standards body will be able to develop a “standard” set of procedures for handling Class 0 devices and assemblies in the foreseeable future.
Class 0 customization includes requirements that are not covered in standards such as CDM (Charged Device Model), CBE (Charged Board Event), CDE (Cable Discharge Event), and EOS. Additionally, recent study into the misdiagnosis of EOS (Electrical Overstress) failures suggests that up to 50% of EOS failures are actually ESD damage due to CBE and CDE. With this discovery, ESD failures are more pervasive than most realize and have become a dominant failure mechanism on the factory floor and in the field. For example, a world class program at AT&T was brought to a virtual standstill in 1988 by a 20 volt CDM device.